Snow sensors and methods for use with same

ABSTRACT

Methods and assemblies for use with snow sensors and snow sensor mechanisms, such as snow removal systems, as well as component combinations and related methods.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.17/735,009, filed May 2, 2022, now allowed and anticipated to issue asU.S. Pat. No. 11,681,076, which is a continuation of U.S. applicationSer. No. 17/347,308, filed Jun. 14, 2021 and issued as U.S. Pat. No.11,320,567, which is a continuation of U.S. application Ser. No.17/111,375, filed Dec. 3, 2020 and issued as U.S. Pat. No. 11,035,982,which claims the benefit of and priority to U.S. Provisional ApplicationSer. No. 62/944,658, filed Dec. 6, 2019. These earlier applications areincorporated by reference in their entireties.

BACKGROUND 1. Field

The present devices and methods relate generally to snow sensors and useof those sensors.

2. Description of the Related Art

Snow, sleet, and ice gauges or sensors (referred to herein simply as“snow sensors”) are devices that sense solid and semi-solidprecipitation, including snow, sleet, ice, hail, graupel, and mixturesof solid and semi-solid precipitation (referred to herein simply as“snow”). Some snow sensors sense the presence of snow or other solid orsemi-solid precipitation (referred to herein simply as “snowfall”).Other snow sensors, such as mechanical probes, provide measurements ofthe depth or quantity of snow. Some snow sensors provide informationabout some quality of snow, such as weight of snow, which may alsoindicate quantity or depth of snow, but in the case of weight, a depthdetermination based on weight will vary depending on the wetness anddensity of the snow.

One example of a gauge for measuring snow is a right circular cylinder,open at the top, which collects snow for instantaneous or latermeasurement. Sometimes, instead, a cylinder or other container may beheated or may include chemicals that melt the snow, where the weight ofthe resulting water is used to estimate a corresponding snow depth. Insome instances, once a known weight of snow or melted snow hasaccumulated, the snow collector ‘tips’ to dispense the measured amountand begin collecting another amount to measure. Another variation uses apair of thermal plates in a cylindrical housing. The first plate ispositioned horizontally and collects snow while the second plate ispositioned vertically under the first plate. The difference in currentneeded to maintain the two plates at the same temperature is used toestimate the precipitation amount and/or rate.

Other gauges sense an ultrasonic or other beam that bounces off the topof the accumulated snow. Examples of designs for these types of devicesmay be found at http://www.howmuchsnow.com/snow/. As described at thissite, ultrasonic gauges are hard to focus, and to obtain an accuratereading from them, the readings must take temperature into account.Gauges that use an infrared light emitting diode (LED) and detect thebounced radiation have a small spot size and costs less than theultrasonic device. The infrared LED is positioned beside a receiver inan assembly mounted parallel to, and facing, the surface to be measured.The intent is for the infrared radiation to bounce off the top of thesnow and be sensed by the receiver, which focuses the reflectedradiation onto a linear CCD array. The location of the reflectedradiation on the receiver is dependent on the distance from the top ofthe accumulated snow to the receiver, purportedly providing ameasurement of snow depth when compared to the known distance to theground or other reference surface. In the example given on abovewebsite, the infrared triangulation measurement sensor used is the SharpGP2D12, and the site includes the specification from Sharp showing theirsensor outputs a non-linear analog voltage corresponding to the distanceof the reflected object.

These gauges work on the theory that snow is opaque and will thereforebounce the radiation off top surface of the snow. However, more oftenthan not, snow contains enough water that it is translucent. This willcause two problems. First, the radiation will reach a point below thesnow surface before it will reflect—a point where the density of thesnow is sufficient to reflect the radiation—and therefore provide anincorrect reading. This same problem may lead the gauge to not detectany snow until after enough has accumulated that the radiation isfinally reflected. This is particularly problematic for systems that aredependent on accurately detecting the presence of snow. Second, when theradiation is reflected from below the actual snow surface, the reflectedradiation may be diffuse and scattered. This diffuse radiation may notbe detected by the receiver at all, or the receiver may have difficultysensing where the diffuse radiation is striking the linear CCD arraythat translates to a distance and a resulting snow depth. As describedat the above website, these gauges also require temperature and sunlightcompensation. Finally, this system is limited by the height of theassembly containing the LEDs and receiver—if the snow is deep enough toreach or cover these components, it will be impossible for the system toreport the snow depth.

Yet other gauges include a series of paired emitters and receivers. Thereceiver is positioned horizontally a known distance from its pairedemitter. The first pair is positioned a known distance relatively closeto the surface on which snow falls. The second pair is positioned aknown distance from the surface, but further from the surface on whichsnow falls and spaced vertically from the first pair. The third pair ispositioned a known, even further, distance from the surface on whichsnow falls and spaced vertically from the second pair. Additional pairsof emitters and receivers are similarly arranged further and furtherfrom the surface on which snow falls. As snow accumulates around andagainst the paired emitters and receivers, the pairs closest to thesurface on which snow falls will, one after the next, be covered bysnow. As the pairs of emitters and receivers are covered by snow, no, orat least less, radiation from the snow-covered emitters will reach theirpaired, snow-covered receiver. The snow depth will correspond to thedistance from the surface on which snow falls to a space between thetopmost sensor/receiver pair that is covered (and providing a small orundetectable reading) and the bottommost sensor/receiver pair that isnot covered with snow (and therefore providing a strong reading). Analternative to this arrangement uses temperature sensors arranged inseries rather than paired emitters and receivers. These are bulky andexpensive gauges.

Variations on the above examples also exist. For instance, some systemsinclude an optical disdrometer, images or other method to take thesize/diameter of flakes/drops into account. As another example, someassemblies use a global positioning system to take measurements of theground surface and then the snow surface, and then compare themeasurements to establish the depth of snow.

Snow sensors have improved over the years. Nevertheless, the presentinventor has determined that existing snow sensors are susceptible to arange of improvements. By way of example, but not limitation, thepresent inventor has determined that it would be desirable to provide asnow sensor that is simpler, that more reliably predicts the presence ofsnow, and is less costly than conventional snow sensors, while alsobeing more compact and user-friendly than conventional snow sensors.

SUMMARY

A snow sensor includes a receiver; a window (if needed) on which snowcan accumulate, positioned on top of the receiver; and one or moreemitters positioned above and spaced apart from the receiver; where theone or more emitters emit radiation, and where any snow accumulatedbetween the emitters and the receiver blocks at least some of theradiation from reaching the receiver, and where the receiver receivesthe remaining radiation and reports a numerical value that correspondsto the remaining radiation received by the receiver. The presentinventions also include snow removal systems with such a snow sensor,snow removal system subassemblies, and related methods.

A snow removal system includes a snow melting component, a snow sensor,and a controller to control the snow melting component, where the snowsensor includes a receiver; a window (if needed), on which snow canaccumulate, positioned on top of the receiver; and one or more emitterspositioned above and spaced apart from the receiver; where the one ormore emitters emit radiation, any snow accumulated between the emittersand the receiver blocks at least some of the radiation from reaching thereceiver, the receiver receives the remaining radiation and reports anumerical value that corresponds to the remaining radiation received bythe receiver, and the controller sends a command to the snow meltingcomponent according to the numerical value reported by the receiver.

A snow sensing method includes providing an artificial source ofradiation and receiving radiation from that artificial source or anatural source or a combination of a natural source and the artificialsource, and reporting a numerical value corresponding to the receivedradiation, particularly when snow is allowed to block the receivedradiation. A snow removal method may involve using this snow sensingmethod and further include providing a snow melting component, comparingthe value reported by the snow sensing method to a threshold value, andcontrolling the snow melting component based on the comparison of thereported valued and the threshold value. Controlling the snow meltingcomponent may further include methods to activate the snow meltingcomponent manually or automatically.

BRIEF DESCRIPTION OF THE DRAWINGS

Detailed description of exemplary embodiments will be made withreference to the accompanying drawings.

FIG. 1A is a perspective view of an exemplary snow sensor in anassembled state.

FIG. 1B is an exploded perspective view of certain components of thesnow sensor illustrated in FIG. 1A, including a top and bottom of thesensor housing.

FIG. 2 is a top view of certain components of the snow sensorillustrated in FIGS. 1A and 1B.

FIG. 3 is a side view of certain components of the snow sensorillustrated in FIGS. 1A and 1B.

FIG. 4 is a view from the back of the snow sensor illustrated in FIGS.1A and 1B.

FIG. 5 shows readings from a receiver as a function of snow depth,comparing the curves for readings in bright sunlight, low sunlight, andno sunlight.

FIG. 6A shows the readings from FIG. 5 with a horizontal line depictinga high sensitivity threshold setting.

FIG. 6B shows the readings from FIG. 5 with a horizontal line depictinga low sensitivity threshold setting.

FIG. 7A is a perspective view of another exemplary snow sensor in anassembled state.

FIG. 7B is an exploded perspective view of certain components of thesnow sensor illustrated in FIG. 7A, including a top and bottom of thesensor housing.

FIG. 7C is an exploded side view of certain components of the snowsensor illustrated in FIG. 7A.

FIG. 7D is a close-up, exploded view of the top of housing post portion702.

FIG. 8 is a top view of certain components of the snow sensorillustrated in FIGS. 7A through 7D.

FIG. 9 is a side view of certain components of the snow sensorillustrated in FIGS. 7A-7D.

FIG. 10 is a view from the back of the snow sensor illustrated in FIGS.7A-7D.

FIG. 11A shows readings, under dark ambient conditions, from a receiver,as a function of snow depth, with a horizontal line depicting an examplelow-sensitivity threshold for dark conditions.

FIG. 11B shows readings, under dark ambient conditions, from a receiver,as a function of snow depth, with a horizontal line depicting an examplemedium-sensitivity threshold for dark conditions.

FIG. 11C shows readings, under dark ambient conditions, from a receiver,as a function of snow depth, with a horizontal line depicting an examplehigh-sensitivity threshold for dark conditions.

FIG. 12A shows readings, under bright ambient conditions, from areceiver, as a function of snow depth, with a horizontal line depictingan example low-sensitivity threshold for bright conditions.

FIG. 12B shows readings, under bright ambient conditions, from areceiver, as a function of snow depth, with a horizontal line depictingan example medium-sensitivity threshold for bright conditions.

FIG. 12C shows readings, under bright ambient conditions, from areceiver, as a function of snow depth, with a horizontal line depictingan example high-sensitivity threshold for bright conditions.

FIG. 13 shows readings from a receiver as a function of snow depths of 1inch to 5 inches, when the exemplary snow sensor was exposed to brightambient conditions, compared to when the snow sensor was exposed to darkambient conditions.

DETAILED DESCRIPTION

The following is a detailed description of the inventions. Thisdescription is not to be taken in a limiting sense, but is made merelyfor the purpose of illustrating the general principles of theinventions.

It should also be noted here that the specification describes structuresand methods that are especially well-suited for use with a system orassembly that detects snow and initiates heating of a surface to preventor remove snow accumulation. Nevertheless, it should be appreciated thatthe present inventions are applicable to a wide variety of systems. Byway of example, but not limitation, the inventions may apply to a systemthat periodically reports an amount of accumulated snow.

Also note that the specification focuses on a snow sensor wired to otherdevices within an assembly and to a power source. But it should beappreciated that the present inventions are applicable to snow sensorsthat, for instance, contain a power source, such as a battery, so do notneed to be hard-wired to a power source as described in more detailbelow. As another non-limiting example, the present inventions are alsoapplicable to snow sensors that communicate with other system deviceswirelessly. By way of example, but not limitation, the inventions mayapply to snow sensors that communicate with other devices within thesystem via Bluetooth® or Wi-Fi™ technology, as described in more detailbelow.

The specification also describes use of a snow sensor that is used in asystem that connects to a cloud server via the internet. Nonetheless, itshould be appreciated that the present inventions are also applicable toother system connectivity. By way of example, but not limitation, thesystem could be connected to and controlled via a private server.

An exemplary snow sensing device, which is generally represented byreference number 100 in FIGS. 1A and 1B, includes a housing top 200 anda housing bottom 300 that, together and as best seen in FIG. 3 , formroughly an “L” shape with a housing base portion 302 and a housing postportion 202. Exemplary housing top 200, which is also shown in FIGS. 2and 3 , encloses one or more emitters, such as infrared (IR) emitters210. The emitters 210 are positioned near the top of post portion 202,above a frame 222 in base portion 302 that holds an optical sensorwindow 224 that, in turn, sits atop an optical sensor board 320.Exemplary housing bottom 300 includes an electronics housing 322 to holdthe optical sensor board 320. As best seen in FIGS. 1B and 4 , housingbottom 300 also has an opening 312 for a wire(s) or connector(s) (notshown) to connect the snow sensing device (a.k.a., snow sensor) 100 topower, the internet, a local network, and/or other system components,such as a controller or a communications system. Alternatively and asmentioned above, snow sensor 100 may be powered internally with one ormore batteries, such as lithium-ion batteries or alkaline batteries, andmay include wireless technology, such as Bluetooth® or WiFi™ components,to communicate wirelessly with a cloud server over the internet or withone or more other system components (not shown), such as one or moreswitches, a control module (a.k.a. controller), a private server, apower source, etc. In yet other alternatives, one or more of these othersystem components may be included in the housing for snow sensor 100,such as a switch and controller.

Infrared emitters 210 may comprise IR light emitting diodes (LEDs)commercially available from Digi-Key Electronics, Arrow Electronics orother distributor of electronic components, such as superbright 5 mm IRLEDs running on 100 mA and emitting a 20 degree beamwidth at awavelength of 940 nanometers. The emitters 210 may be placed on a boardthat may include other electronic components, such as, for example,resisters and/or other components to monitor emitters 210 to verify theyare working and/or to protect emitters 210, e.g., in case of a voltagespike.

The type and number of IR emitters 210 may vary depending on the othersnow sensor components used, particularly receiver chip 321, which isdescribed further below. The type and number of emitters 210 is alsodependent on the purpose for the snow sensor and the other systemcomponents used for the purpose, and on any limits placed on the spacedesignated for the emitters 210 or any limits on the size of the housingportion containing the emitters 210. For instance, if snow sensor 100 isused in an assembly that detects snow and initiates heating of a surfaceto prevent or remove snow accumulation, the IR emitters 210 arepreferably bright enough to provide a choice of sensitivity, asdescribed further below, but not so bright that its radiation, combinedwith IR radiation from sunlight, overwhelms receiver 321 and defeats orreduces its ability to provide a legitimate or accurate reading. Inaddition, emitters 210 and sensor board 320 may be chosen to emit andsense other types of radiation. By way of examples and not limitation,other types of electromagnetic radiation may be emitted and sensed, suchas visible light or ultraviolet radiation, or other types of radiationmay be emitted and sensed, such as ultrasonic acoustic radiation.

Optical sensor board 320 may include a receiver chip 321 and relatedelectronics. For instance, optical sensor board 320 may be a custom-madeboard that includes electronic components that are appropriate to thepurposes of snow sensor 100 and that are needed to interfaceappropriately with receiver chip 321 and any other parts in the systemusing snow sensor 100. Receiver chip 321 may comprise an integratedcircuit (IC) with integrated IR proximity detector commerciallyavailable from Digi-Key Electronics, Arrow Electronics or otherdistributor of electronic components, such as Vishay Semiconductor OptoDivision's TSOP38238. Those of ordinary skill in the art will be awareof the additional electronic components necessary to interface with chip321 and appropriate for their particular use and purpose of snow sensor100. For instance, if snow sensor 100 is used in an assembly thatdetects snow and initiates heating of a surface to prevent or removesnow accumulation, the components may include a microcontroller andwiring to a switch that turns a heat tape on and off, resisters andcapacitors to keep the chip 321 stable and protected from voltagespikes, etc., and may also include a communications chip forcommunicating with, e.g., a control module (a.k.a. controller). One ormore of these additional electronic components may be separate,stand-alone components enclosed by housing top 200 and housing bottom300, rather than placed on board 320. And as mentioned earlier, thehousing for snow sensor 100 may also house a switch(es) and/orcontroller.

Depending on the use of snow sensor 100, optical sensor window 224 maybe made of weather-proof or weather-resistant material transparent tothe type of radiation emitted and sensed. In the case of IR emitters 210and receiver chip 321, optical sensor window 224 may be glass, since anymaterial that is not or does not remain IR-transparent may impact thesensitivity and/or effectiveness of snow sensor 100. In otheralternatives, a separate window 224 may not be needed, as it may beintegrated into receiver chip 321 or board 320. Housing top 200 andhousing bottom 300 may be made from the same material or from compatiblematerials. For instance, they may both be made from ABS plastic or otherweather resistant plastic.

Use of snow sensor 100 will now be addressed. For some uses of snowsensor 100, it is most important to know whether or not any snow hasfallen. For other uses, it is also or instead more important to know howmuch snow has fallen, i.e., snow depth. In use, snow sensor 100 may beconnected to other devices, as previously described, via wire orwirelessly. For instance, snow sensor 100 may be connected to a devicethat periodically reports a depth of snow. This device may receivereadings from the sensor and translate those into values of snow depth.As another example, snow sensor 100 may be connected to a snow removalsystem, such as a system using heat tape or other snow melting componentinstalled on or in the roof of a building, such as a home or hotel orother business, or on or in a walkway or driveway, or on piping. Thissystem may include a controller to interpret readings from the sensorand act according to predetermined instructions or it may report thesensed data and wait for instructions in response. If snow sensor 100 isconnected to such a snow removal system, it may be more important toknow that any snow has or is falling, so the snow removal system may beautomatically or manually activated.

Therefore, in some embodiments, snow sensor 100 reports or provides anumber that corresponds to the amount of radiation that is sensed byreceiver 321—this value varies (drops) as snow falls and accumulates onsnow sensor 100 and it also varies (increases) as snow melts and/or isevaporated off of snow sensor 100. As further examples, snow removal mayoccur from any one of, or combinations of, the following: snow meltingand/or evaporating from the heat of the sun, outside temperature, orsome other natural method; snow melting and/or evaporating from a sourcesuch as the heat from a heated electrical wire (such as a heat tapesystem), heat from a roof radiated from inside a building, or any otherartificial heating source; physical/mechanical snow removal such as fromthe wind, or naturally falling off of a roof due to the weight of thesnow and the pitch of the roof, or any other naturally occurring method;physical/mechanical snow removal with a snow rake, shovel, leaf blower,or any other artificial method. The snow removal discussed herein mayoccur mainly to snow melting components discussed herein, but may beaided by one or more of these other snow removal methods or mechanisms.Similarly, the IR or other radiation that is sensed by receiver 321 orother receiver may be naturally occurring radiation, such as from thesun, or from an artificial source, such as IR emitters or otherartificial source of IR or other radiation.

Returning to the example of snow sensor 100 including a first exemplaryreceiver 321, if no snow or any other obstruction is located between theemitters 210 and receiver 321, snow sensor 100 may report a firstnumber, indicating that no snow has fallen. The number reported may be,for example, a resistance value that corresponds to the intensity ofradiation striking receiver 321. Since the inventor's testing has shownthat snow is translucent, not opaque, as snow accumulates on sensor 100,the number reported from exemplary receiver 321 will decrease, and thenumber will continue to decrease as more and more snow accumulates, butthe number will not decrease to zero until radiation from emitters 210(and any from the sun) is fully blocked from reaching receiver 321.

Depending on the receiver 321 and emitter 210 and other variablesdiscussed below, an initial value reported when there is no obstructionbetween receiver 321 and emitter 210 may be somewhere between about 5000and about 15000. As snow begins to fall on sensor 100, the reportedvalue will begin to decrease from this initial value. As a firstexample, the value may drop by about 200 to about 800 when about 2 toabout 4 inches of snow has fallen on sensor 100. As a second example,the value may drop by about 400 to about 1000 after about to about 7inches of snow has accumulated on sensor 100. Ranges are provided herebecause these values are dependent on many variables, such as theemitter(s) 210 chosen, the receiver 321 used, the amount of radiationfrom the sun being detected (if any) along with radiation fromemitter(s) 210, whether the sun has gotten more or less obstructedbetween readings, and the type of snow falling. For instance, theinventor's testing has shown that wet snow (i.e., snow with a relativelyhigher water content than dry snow) is more translucent than dry snow,so the values reported will drop more slowly as wet snow accumulates onsensor 100 compared with drier snow.

As shown in FIG. 5 , when there is no sunlight, such as at nighttime (inmost locations), the snow sensor reports values that fall along a firstcurve 510. In bright sunlight, snow sensor 100 reports values that fallalong a second curve 520. And in low light, snow sensor 100 reportsvalues that fall along a third curve 530, positioned between curves 510and 520 in FIG. 5 . This depiction shows that when there is no snow, thevalue reported by snow sensor 100 can vary, as explained above, and inthis case, is varying based on the amount of sunlight reaching receiver321. The values reported in various amounts of sunlight will continue tovary by lesser and lesser amounts as snow accumulates between receiver321 and emitters 210. Once so much snow has covered optical sensorwindow 224 that receiver 321 cannot detect any radiation, the curvesmeet and the value reported under all sunlight conditions is zero.

As an example, snow sensor 100 with Vishay Semiconductor Opto Division'sTSOP38238 IC as an exemplary receiver 321 and two superbright 5 mm IRLEDs (as described above) as exemplary emitters 210 were connected to anautomated snow removal test system. When there was no snow or otherobstruction between emitters 210 and receiver 321, and there was brightsunlight, the inventor found that the initial value reported by receiver321 was about 6500 (the maximum reading for this receiver chip 321). Assnow began to fall, the value reported by receiver 321 decreasedquickly, to about 200 when there was about 1.5 inches of snow betweenemitters 210 and receiver 321. Once about 2 inches to about 2.5 inchesof snow accumulated on sensor 100, output from receiver 321 reachedzero, since no radiation was reaching receiver 321.

An automated snow removal system attached to the snow sensor 100 fromthe immediately preceding example might include a controller toautomatically activate a snow melting component if the value reported byreceiver 321 falls by a certain amount. For instance, the system mightactivate if the value falls from 6500 to 100. In some embodiments,however, a user may set the sensitivity of the system. For instance, andas shown with line A in FIG. 6A, if a user sets the system to highsensitivity, the system activates snow removal (e.g., turns on the heattape on a roof) after the value reported from receiver 321 drops acertain amount from the initial value. But if the system is set to alower sensitivity, as shown with line B in FIG. 6B, the value reportedfrom receiver 321 needs to drop by a larger amount from the initialvalue before the system activates snow removal.

This sensitivity setting is a useful feature in many situations. Someusers may want to activate the snow removal system as soon as a verysmall amount of snow is detected, so there is very little chance thatany snow or icy conditions exist on the surface being warmed. Otherusers might choose to let a larger amount of snow accumulate beforeactivating the system, which may save power and therefore money. Asanother example, if the system is heating a walkway, but the user is nothome, that user may allow more snow to accumulate before activating thesystem, but that same user may want the system to activate immediatelyif they are at home. Another possibility is the system may be connectedto a weather station or weather forecast readout. If very little snow ispredicted, and especially if sunlight is predicted to follow the snow,the system may delay a certain amount of time based on that forecast.Even if the system is not connected to a weather station or forecastreadout, in a case like this, the user may follow the forecast andchange the sensitivity to a low setting so the system is unlikely toturn on, if the user prefers to allow the forecast sunlight to melt thesnow. While FIGS. 6A and 6B depict two sensitivity settings, there maybe three sensitivity setting (high, medium, low) or more, or the systemmay be infinitely variable, using a physical or software slider,rheostat, potentiometer or the like to set the sensitivity.

For instance, the automated snow removal test system described earlierwas set to high sensitivity. As a result, the system automaticallyactivated a heat tape when the value reported from receiver 321 droppedfrom 6500 to 200. In other words, when the value reached 200, the systemcontroller automatically activated the heat tape, and the heat tape onthe test roof began to melt the snow that had fallen. As snow continuedto accumulate on sensor 100, the value reported by receiver 321 alsocontinued to fall, and the system continued to heat the roof and meltthe snow. Once the value reported by receiver 321 returned to andexceeded 200, the system controller automatically shut off the heattape.

In order to replicate or at least closely approximate the amount of snowon the roof or other surface that is heated once the automated snowremoval system activates, snow sensor 100 may be placed where heat fromthe heat tape or other heating element or heat source causes snow onsensor 100 to melt. For instance, the position of snow sensor 100 may bechosen so the snow on sensor 100 is not among the first snow melted bythe heat source, and also not among the last snow to be melted. Rather,sensor 100 may be positioned about half the distance between the heatsource and where the heat source has the smallest effect.

In this example position, combined with the example above where the snowremoval test system is set to high sensitivity, once the systemcontroller activates snow removal (when snow sensor 100 outputs areading of 200), snow that is close to the heat source begins to meltfirst—before the snow on sensor 100—and snow on sensor 100 begins tomelt before snow that is further from the heat source. If theprecipitation rate is greater than the rate of melting at sensor 100,snow will continue to accumulate and the value reported by snow sensor100 will continue to decline. Once the rate of melting at sensor 100exceeds the precipitation rate, the value reported by snow sensor 100will increase. Once receiver 321 detects enough radiation to report avalue greater than 200, the controller will automatically shut off theheat source. Again, with the above system configuration, if the sun isbright, this will occur when there is about 1.5 inches of snow.

In yet another example, with the above configuration and placement ofsnow sensor 100, if it is dark outside, and there is no snow blockingradiation from these exemplary emitters 210, this exemplary receiver 321reports a value of about 2600. As above, if the system is set to highsensitivity, the snow removal system will automatically activate whenthe value reported by receiver 321 drops to 200. Testing when there wasno ambient light (e.g., at nighttime) found that this occurred whenthere was about 0.5 to about 1 inch of snow on the sensor. Once about 2to about 2.5 inches of snow accumulated between emitters 210 andreceiver 321, output from snow sensor 100 reached zero, since noradiation was reaching receiver 321. (As can be seen from FIG. 5 , thevalue output by sensor 100 reaches zero for all sunlight conditions atthe same snow depth.) As snow continued to accumulate on sensor 100, thevalue reported by receiver 321 decreased, and the system continued toheat the roof and melt the snow. Once the value reported by receiver 321returned to and exceeded 200, the snow removal system controllerautomatically shut off the heat source.

In some embodiments, as in the preceding examples, the system was setupto act according to predetermined instructions. That is, the snowremoval system was automated so the heat source switched on when thevalue reported by receiver 321 reached a certain set value (based onsensitivity chosen). The system controller switched off the heat sourcewhen the reading from receiver 321 returned to that same set value. Forinstance, if set to low sensitivity, the above exemplary configurationof snow sensor 100 would activate snow removal when the reading outputfrom receiver 321 decreased to about 30 or about 25. As describedearlier, no matter the sunlight conditions or the sensitivity setting,this configuration of snow sensor 100 reported a value of zero once thesnow accumulated between emitters 210 and receiver 321 reached about 2to about 2.5 inches of snow. When set to low sensitivity, thisconfiguration then turned the snow removal system heat source back offonce the reading from receiver 321 increased to about 25 to about 30.

In other embodiments, and as mentioned earlier, the system may haveadditional sensitivity settings, such as medium sensitivity, medium-low,medium-high, etc. Or the system may have an infinite range ofsensitivities, using an electronic slider or potentiometer or the liketo set the sensitivity.

In yet other embodiments, the system can be operated manually. Forexample, a user may monitor the value output by receiver 321 andactivate the snow removal system when they desire. In the case describedearlier where the system communicates wirelessly with a cloud serverover the internet, the user may send commands from their computer,tablet, smart phone or the like. The system controller then switches theheat tape or other snow removal heat source on and off as commandedmanually by the user. As mentioned above, the system may instead bestand-alone, either with a private server, or it may be hard-wiredtogether. If hard-wired together, the user would be in physicalproximity to manually operate the system.

In any of these embodiments and examples, the system may include athermometer that reports the temperature in the vicinity of the snowsensor 100, or a thermometer may be built into snow sensor 100. This maybe advantageous in instances where receiver 321 reports a decrease invalue but the measured temperature is well above freezing. In that case,it may be that a leaf or dust or other obstruction is obscuring theradiation from emitters 210, rather than snow. The user may then checksnow sensor 100, or the system may even alert the user to check the snowsensor 100. In other embodiments, the system may be set to operate onlybelow a certain temperature, or only in a certain temperature range. Forinstance, the system may allow the heat tape to be activated only if thetemperature is between 10° Fahrenheit (F) and 35° F. The temperature ortemperatures at which the system will be allowed to operate may bepredetermined or, in some systems, may be set by the user.

Another exemplary snow sensing device, generally represented byreference number 600 in FIGS. 7A-7D, includes a housing top 700 and ahousing bottom 800. As above, housing top 700 and housing bottom 800 maybe made from the same or compatible materials, such as ABS plastic orother weather resistant plastic. Also as above, and as best seen in FIG.9 , snow sensor 600 forms roughly an “L” shape with a housing baseportion 802 and a housing post portion 702. In this example, anelectronics board 804 is inserted from below into housing bottom 800 andsecured with screws 805, but board 804 may be held in place with by anyother sufficient means. In addition, snow sensor 600 (or sensor 100) mayalso include a mounting plate 806 for securing the snow sensor to a roofor other surface. The plate 806 may be held to the snow sensor using afirst set of screws (not shown) to attach plate 806 to housing bottom800 and held to a roof or other surface using screws (not shown) placedin through-holes 807, or via other sufficient attachment means. Those ofskill in the art will recognize other techniques and means for securingthese snow sensors, such as clips, clamps, bolts, anchors, clecos,cords, adhesives, and the like.

As seen well in FIGS. 7B and 7C, an exemplary housing top 700 and shroud722 fit into position within housing bottom 800. One or more emitters,such as infrared (IR) emitter 710, is positioned near the top of postportion 702 and in line with a first cut-out area 722 a in shroud 722and an emitter window portion 723 of housing top 700. Housing top 700may also include an optical sensor window portion 724 that is positionedabove a second cut-out area 722 b in shroud 722. Depending on the use ofsnow sensor 600, including the type of radiation being sensed and theenvironment in which it is used, housing top 700, including windowportions 723 and 724, and shroud 722 may be made of a variety ofmaterials. For instance, housing top 700 (or at minimum the portionssituated between emitter 710 and receiver 821) may be made of atranslucent plastic that is “invisible” to IR and, ideally, resistant tomold, fogging, and condensation. In other alternatives, window portion723 may not be needed, as window 723 may be integrated into receiverchip 321 or board 320, and window portion 724 may not be needed ifwindow 724 is integrated into emitter(s) 710. Similarly, shroud cut-outareas 722 a and 722 b may not be needed in some embodiments, or shroud722 may not be needed at all, if, for instance, shroud 722 is integratedwith housing top 700 or housing bottom 800. Exemplary housing bottom 800may include a housing (not shown) for electronics board 804 or board 804may be secured in place as described earlier. Electronics board 804holds receiver chip 821 (not shown) and other electronics describedherein and/or others, such as a microcontroller and communicationselectronics, known in the art.

As best seen in FIGS. 8 and 10 , housing bottom 800 also has an opening812 for a wire(s) or connector(s) (not shown) to connect snow sensor 600to power, the internet, a local network, and/or other system components,such as a controller or a communications system. Alternatively and asmentioned above, snow sensor 600 may be powered internally with one ormore batteries, such as lithium-ion batteries or alkaline batteries, andmay include wireless technology, such as Bluetooth® or WiFi™ components,to communicate wirelessly with a cloud server over the internet or withone or more other system components (not shown), such as one or moreswitches, a control module (a.k.a. controller), a private server, apower source, etc. In yet other alternatives, one or more of these othersystem components may be included in the housing for snow sensor 600,such as a switch and controller.

Infrared emitter 710 may comprise one or more IR light emitting diodes(LEDs), such as OSRAM Opto Semiconductors Inc.'s SFH 4059-QS IR emitterscommercially available from Digi-Key Electronics, Arrow Electronics orother distributor of electronic components. As best seen in FIG. 7D,which is a close-up, exploded view of the top of housing post portion702, emitter 710 may be placed on a board 711 that may include otherelectronic components, such as, for example, resisters and/or othercomponents to monitor emitter 710 to verify it is working and/or toprotect emitters 710, e.g., in case of a voltage spike. The board may besecured to a bracket 713 with glue, other adhesive, a screw 715 a orother sufficient means. Bracket 713 may be held to housing bottom 800with glue, other adhesive, a screw 715 b or other sufficient means.

As described above, the type and number of IR emitters 710 may varydepending on snow sensor purpose and other components used, particularlyreceiver chip 821. Receiver chip 821 may be positioned on electronicsboard 804 with additional electronics as discussed above in relation tooptical sensor board 320 and receiver chip 321, such as one or moremicrocontrollers, switches, resistors, capacitors, communications chip,and the like. Receiver chip 821 may comprise an integrated circuit (IC)with integrated IR proximity detector such as Silicon Laboratories'Si1151-AB00-GM IC commercially available from Digi-Key Electronics,Arrow Electronics or other distributor of electronic components. Asnoted for above embodiments, additional electronic components tointerface with chip 821 will vary based on use and purpose of snowsensor 600, such as microcontroller and wiring to a switch that turns aheat tape on and off, resisters and capacitors to keep the chip 821stable and protected from voltage spikes, etc., a communications chipfor communicating with, e.g., a control module (a.k.a. controller),and/or other components known to those of skill in the art. One or moreof these additional electronic components may be separate, stand-alonecomponents enclosed by housing top 700 and housing bottom 800, ratherthan placed on board 804. And as mentioned earlier, the housing for snowsensor 600 may also house a switch(es) and/or controller.

Use of alternative snow sensor 600 will now be addressed. As above, forsome uses of snow sensor 600, it may be most important to know whetheror not any snow has fallen. For other uses, it is also or instead moreimportant to know how much snow has fallen, i.e., snow depth. In use,snow sensor 600 may be connected to other devices, as previouslydescribed, via wire or wirelessly. For instance, snow sensor 600 may beconnected to a device that periodically reports snow depth. This devicemay receive readings from the sensor and translate those into values ofsnow depth. As another example, snow sensor 600 may be connected to asnow removal system, such as a system using heat tape or other snowmelting component installed on or in the roof of a building, such as ahome or hotel or other business, or on or in a walkway or driveway, oron piping. This system may include a controller to interpret readingsfrom the sensor and to act according to predetermined instructions, orit may report the sensed data and wait for instructions in response. Ifsnow sensor 600 is connected to such a snow removal system, it may bemore important to know that any snow has or is falling, so the snowremoval system may be automatically or manually activated.

Therefore, in some embodiments, snow sensor 600 reports or provides anumber that corresponds to the amount of radiation that is sensed byreceiver 821—this value varies (drops) as snow falls and accumulates onsnow sensor 600 and it also varies (increases) as snow melts and/or isevaporated off of snow sensor 600. For instance, in the example of snowsensor 600 including a first exemplary receiver 821, if no snow or anyother obstruction is located between the emitter 710 and receiver 821,snow sensor 600 may report a first number, indicating that no snow hasfallen. The number reported may be, for example, a resistance value thatcorresponds to the intensity of radiation striking receiver 821, to anupper theoretical limit of 65,536, which is 2 to the power of 16. Asdescribed above, the inventor's testing has shown that snow istranslucent, not opaque, so as snow accumulates on sensor 600, thenumber reported from exemplary receiver 821 will decrease, and thenumber will continue to decrease as more and more snow accumulates, butthe number will not decrease to a lower theoretical limit of zero untilradiation from emitters 710 (and any from the sun) is fully blocked fromreaching receiver 821. The inventor has found that a sensitive receivermay never report a value of zero due to the infrared radiation generatedby the snow sensor itself, and sensed by the receiver.

Depending on the receiver 821 and emitter 710 and other variablesdiscussed below, an initial value that is reported by the receiver 821when there is no obstruction between receiver 821 and emitter 710 may besomewhere between about 600 and about 65000. As can be seen well inFIGS. 11A-11C, the initial value is about 600 to about 700 when there isno sunlight and no obstruction between the activated emitter 710 andreceiver 821. As seen well in FIGS. 12A-12C, when there is directsunlight and no significant obstruction between the sunlight andreceiver 821, the receiver 821 initial value is about 60,000 to about65,000, indicating that the receiver 821 is close to its maximum readingdescribed above.

The inventor has determined that more sensitive sensors like sensor 600,when exposed to direct sunlight, provide readings from receiver 821 thatchange insubstantially or not at all when emitters like emitter 710 areactivated versus off. When readings with and without emitter 710activated are the same or similar, then the sensor is in direct sunlightor high light conditions, the values sensed will be similar to thoseshown in the curve of FIGS. 12A-12C, and the thresholds may be set atvalues similar to those shown in FIGS. 12A-12C. In those cases, it maybe beneficial, whenever the sensor is checked, to take a reading withemitter 710 activated and a reading with emitter 710 off. Alternatively,if a given set of readings are similar, the emitter may remain off for atime, such as 5 or 10 minutes, before a next comparison of readings withemitter 710 activated and off. This may be preferable in cases where thesensor takes readings often, such as every five seconds or even morefrequently, particularly if it is undesirable to activate emitter 710 sofrequently, especially if it was recently established that the sensor600 is in high light conditions.

As snow begins to fall on sensor 600, the reported value begins todecrease from the value reported when there is no obstruction betweenactivated emitter 710 and receiver 821. A first set of examples isdepicted in FIGS. 11A-11C, resulting from tests of snow sensor 600 withOSRAM Opto Semiconductors Inc.'s SFH 4059-QS IR emitter as an exemplaryemitter 710 and Silicon Laboratories' Si1151-AB00-GM IC as an exemplaryreceiver 821. As shown in the curve shared by FIGS. 11A-C, when there isno ambient light and emitter 710 is activated, the initial reading ofbetween about 600 and about 700 may drop to between about 350 and about450 when about half an inch of snow accumulates on sensor 600; may dropto between about 100 and about 200 when about 2.5 to 3 inchesaccumulate; and may drop to between about 10 and about 20 when about 4or more inches accumulate on the sensor. In other words, and as shown inFIGS. 11A-11C, in this example of no ambient light, such as would be thecase at nighttime (in most locations), snow sensor 600 reports valuesthat fall roughly along a first curve 910.

As a second set of examples, and as depicted in FIGS. 12A-12C, whenthere is direct sunlight, the value may drop from between about 60,000and about 65,000 to between about 7000 and about 9000 when about half aninch of snow has fallen on sensor 600; may drop to between about 900 andabout 1200 when about 2.5 to 3 inches have fallen; and may drop tobetween about 50 and about 250 when about 4 or more inches have fallen.In other words, in this example of bright ambient light, snow sensor 600reports values that fall roughly along a second curve 920, shown inFIGS. 12A-12C. As in earlier examples, ranges are provided because thesevalues are dependent on many variables, such as the emitter(s) chosen,the receiver used, the amount of radiation from the sun being detected(if any) along with radiation from emitter(s), whether the sun hasgotten more or less obstructed between readings, and the type of snowfalling (e.g., wet versus dry snow, as described above).

As explained above, when there is no snow, the value reported by snowsensor 600 can vary based on the amount of ambient light reachingreceiver 821. As seen in FIG. 13 , the values reported in variousamounts of ambient light will continue to vary by lesser and lesseramounts as snow accumulates between receiver 821 and emitters 710. Inthis example, FIG. 13 , shows the values reported by receiver 810 forsnow levels from one to five inches deep when in direct sunlight oncurve 930 and with no ambient light but with emitter 710 activated alongcurve 940. Theoretically, the curves will meet and the value reportedunder all sunlight conditions will be zero once so much snow coversoptical sensor window 724 that receiver 821 cannot detect any radiation.But as explained earlier, the radiation emitted by more sensitive snowsensors like sensor 600 will be detected by receiver 821, so thereadings never reach zero. For some receivers, a value of zero is onlyreported to indicate a problem with or failure of the receiver.

An automated snow removal system attached to the snow sensor 600 fromthe immediately preceding example might include a controller toautomatically activate a snow melting component if the value reported byreceiver 821 falls by, to, or beyond a certain amount. For instance, thesystem might activate if the value falls from 63,000 to 10,000 whenthere is sunlight, and might activate if the value falls from 630 to 500when there is no sunlight. In some embodiments, however, a user may setthe sensitivity of the system. For instance, and as shown with line C inFIG. 11C and line F in FIG. 12C, if a user sets the system to highsensitivity, the system activates snow removal (e.g., turns on the heattape on a roof) after the value reported from receiver 821 drops acertain amount from the initial value. But if the system is set to alower sensitivity, as shown with lines A and B in FIGS. 11A and 11B,respectively, and lines D and E in FIGS. 12A and 12B, respectively, thevalue reported from receiver 821 needs to drop by a larger amount fromthe initial value before the system activates snow removal. The valueschosen for high, medium, and low sensitivity may be established inadvance, may be customizable with a user interface, may be implementedin firmware that can be updated remotely, or the like. For instance,there may be an advanced user screen that allows a sophisticated user tomanually enter values to override those that are supplied in firmware.

As described earlier, this sensitivity setting is a useful feature inmany situations since some users may want to activate snow removal assoon as a very small amount of snow is detected (so there is littlechance any snow or icy conditions exist on the surface being warmed),while others might choose to let a larger amount of snow accumulatebefore activating the system (which may save power and therefore money).And as also described earlier, a user may want to activate the systemearlier if, for instance, they are home, but later if they are not. Aswith the earlier sensor examples, the system may be connected to aweather station or weather forecast readout and delay if very littlesnow is predicted, especially if sunlight is predicted to follow thesnow. Or if the system is not connected to a weather station or forecastreadout, a user may follow the forecast and lower the sensitivity so thesystem is unlikely to turn on, if the user prefers to allow the forecastsunlight to melt the snow. While FIGS. 11A-11C and 12A-12C depict threesensitivity settings, there may be more, or the system may be infinitelyvariable, using a physical or software slider, rheostat, potentiometeror the like to set the sensitivity.

Another feature that may be included in these snow removal systemsutilizing these snow sensors is a “quiet” or delay period followingeither switching on the system or turning the system off, or both. Thisfeature can guard against what is termed “bouncing”—when readings arewavering around a setpoint and would otherwise cause the system torepeatedly turn off and on. For instance, if the system depicted in FIG.12A is set to low sensitivity and, while in direct sunlight, readingsare decreasing and reach 1500, the snow removal system should beactivated. If a next reading is taken, e.g., 5, 10, or even 30 secondslater and produces a reading of 1501, it may be better to wait a fewminutes, or to verify that the upward trend continues, before quicklydeactivating the snow removal system. In the same sense, if the systemdepicted in FIG. 11C is set to high sensitivity, and it is a dark night,so the emitter(s) are activated, if the snow removal has been activatedand causes enough snow to melt that the readings are increasing, if thereadings reach or exceed 300, the snow removal system should be set tooff. If a next reading finds the value is 299, it may be better to waita certain time or to check if the readings continue a downward trendbefore again activating the snow removal system. If, for instance, snowbegan falling at a faster rate than before, it may be preferable to turnthe system back on. But if instead the moon had come out from behindclouds and then gone back behind clouds, it would be better to waitand/or get additional readings before reactivating the snow removalsystem.

A more sensitive snow sensor, like sensor 600, that produces readingslike those in FIGS. 11A-13 (as opposed to a simpler system like sensor100 that works as described above with reference to FIGS. 5-6B), will beable to determine whether to use the reading with emitter (e.g., one ormore LEDs) on or off. Once this determination is made, the system willcompare the relevant reading to its sensitivity setting (e.g., the valuefor high, medium or low) for that light condition. For instance, todetermine whether a system set to high sensitivity should use, e.g., 300or 2000 as its high-sensitivity threshold per FIGS. 11C and 12C, thesensor first takes a reading with emitter 710 and another reading withemitter 710 off. If the readings are the same, or if the reading withemitter 710 on is only slightly higher (e.g., one or just a few pointshigher) than with emitter 710 off, then the system uses thehigh-sensitivity threshold for bright sunlight conditions, as shown inFIG. 12C. The reading with emitter 710 off will then be compared to thehigh-sensitivity threshold for bright conditions, which, in thisexample, is 2000. If the reading is below 2000, the snow removalcomponent (e.g., heat tape) is activated, and if the reading is above2000, it is not activated.

For instance, if the reading was 1900, the system automaticallyactivates the heat tape, since the value reported from receiver 821dropped below 2000, and the heat tape begins to melt the snow that hadfallen. As snow continues to accumulate on sensor 600, the valuereported by receiver 821 also continues to fall, and the systemcontinues to heat, e.g., a roof, and melt the snow. Once the valuereported by receiver 821 returns to and exceeded 2000, the systemcontroller automatically shuts off the heat tape. As described earlier,the positioning of the sensor in relation to heat tape or other snowmelting component may be chosen so the snow on sensor 600 is not amongthe first snow melted by the snow melting component, and also not amongthe last snow to be melted. Rather, sensor 600 may be positioned abouthalf the distance between the snow melting component and where the snowmelting component has the smallest effect.

In another example, if the readings with emitter 701 on and off are verydifferent (e.g., 50 with emitter 710 off and 220 with emitter 710 on),the system uses the sensitivity thresholds for dark conditions, whichare shown in FIGS. 11A-11C, and the reading with emitter 710 on. In thisscenario, if the system is set to low sensitivity, the system will notactivate the snow melting component, because the reading of 220 is abovethe low-sensitivity threshold of 200. However, if the system is set tomedium (or high) sensitivity, the system will activate the snow meltingcomponent, because the reading of 220 is below the medium-sensitivitythreshold of 250 (and the high-sensitivity threshold of 300), shown inFIG. 11B.

In some embodiments, as in the preceding examples, the system was setupto act according to predetermined instructions. That is, the snowremoval system was automated so the snow melting component switched onwhen the value reported by receiver 821 dropped to a certain set value(based on low, medium, or high sensitivity chosen). The systemcontroller switched off the snow melting component when the reading fromreceiver 821 increased and returned to that same set value. In otherembodiments, and as mentioned earlier, the system may have additionalsensitivity settings, such as medium-low, medium-high, etc. Or thesystem may have an infinite range of sensitivities, using an electronicslider or potentiometer or the like to set the sensitivity.

In yet other embodiments, the system can be operated manually. Forexample, a user may monitor the value output by receiver 821 andactivate the snow removal system when they desire. In the case describedearlier where the system communicates wirelessly with a cloud serverover the internet, the user may send commands from their computer,tablet, smart phone or the like. The system controller then switches theheat tape or other snow melting component on and off as commandedmanually by the user. As mentioned above, the system may instead bestand-alone, either with a private server, or it may be hard-wiredtogether. If hard-wired together, the user would be in physicalproximity to manually operate the system.

In any of these embodiments and examples, the system may include athermometer that reports the temperature in the vicinity of the snowsensor 600, or a thermometer may be built into snow sensor 600. This maybe advantageous in instances where receiver 821 reports a decrease invalue but the measured temperature is well above freezing. In that case,it may be that a leaf or dust or other obstruction is obscuring theradiation from emitter 710, rather than snow. The user may then checksnow sensor 600, or the system may even alert the user to check the snowsensor 600. In other embodiments, the system may be set to operate onlybelow a certain temperature, or only in a certain temperature range. Forinstance, the system may allow the snow removal component to beactivated only if the temperature is between 10° Fahrenheit (F) and 35°F. The temperature or temperatures at which the system will be allowedto operate may be predetermined or, in some systems, may be set by theuser.

Various methodologies and systems are presented here in the context ofthe exemplary structures described in the preceding sections, andillustrated in the figures, for the purpose of explanation only.Although the present methodologies and systems may employ the structuresshown in the figures and described above, they are not limited thereto.For instance, while the above snow sensors, systems, and methods havebeen described and illustrated with respect to certain dimensions,sizes, shapes, arrangements, singular/plural components, materials, andmethods, in some embodiments, a sensor, system or method that isotherwise substantially similar in construction and function to any ofthe above-discussed embodiments may include one or more differentdimensions, sizes, shapes, arrangements, plural/singular components, andmaterials, may be utilized according to different methods. Additionally,embodiments of the present inventions may incorporate any one,combinations of less than all, or all of the methodologies or devicesreferenced above.

Although the inventions disclosed herein have been described in terms ofthe preferred embodiments above, numerous modifications and/or additionsto the above-described preferred embodiments would be readily apparentto one skilled in the art. By way of example, but not limitation, thepresent snow sensor assemblies may be incorporated into a weatherstation. It is intended that the scope of the present inventions extendsto all such modifications and/or additions and that the scope of thepresent inventions is limited solely by the claims set forth below orlater added.

Finally, with respect to terminology that may be used herein, whether inthe description or the claims, the following should be noted. The terms“comprising,” “including,” “carrying,” “having,” “containing,”“involving,” and the like are open-ended and mean “including but notlimited to.” Ordinal terms such as “first”, “second”, “third,” do not,in and of themselves, connote any priority, precedence, or order of oneelement over another or temporal order in which steps of a method areperformed. Instead, such terms are merely labels to distinguish oneelement having a certain name from another element having a same name(but for the ordinal term) to distinguish the elements. “And/or” meansthat the listed items are alternatives, but the alternatives alsoinclude any combination of the listed items. The terms “approximately,”“about,” “substantially” and “generally” allow for a certain amount ofvariation from any exact dimensions, measurements, and arrangements, andshould be understood within the context of the description and operationof the invention as disclosed herein. Terms such as “top,” “bottom,”“upper,” “lower,” “above,” and “below” are terms of convenience thatdenote the spatial relationships of parts relative to each other ratherthan to any specific spatial or gravitational orientation. Thus, theterms are intended to encompass an assembly of component partsregardless of whether the assembly is oriented in the particularorientation shown in the drawings and described in the specification, orany other rotational variation therefrom.

What is claimed is:
 1. A method, comprising: sensing snow accumulationby emitting radiation from at least one emitter downwardly toward anupwardly facing receiver in such a manner that snow accumulated betweenthe at least one emitter and the receiver blocks at least some of theradiation from reaching the receiver and the upwardly facing receiverreceives radiation that is not blocked by the snow.
 2. The methodclaimed in claim 1, wherein the at least one emitter comprises aplurality of emitters.
 3. The method claimed in claim 1, wherein theradiation that is not blocked by the snow comprises radiation from theat least one emitter.
 4. The method claimed in claim 1, wherein theradiation that is not blocked by the snow comprises radiation from anatural source or from a combination of the at least one emitter and thenatural source.
 5. The method claimed in claim 4, wherein the naturalsource comprises the sun.
 6. The method claimed in claim 1, furthercomprising reporting at least one numerical value that corresponds tothe radiation received by the receiver.
 7. The method claimed in claim6, wherein the at least one numerical value comprises a plurality ofnumerical values.
 8. The method claimed in claim 6, wherein the at leastone numerical value is reported by the receiver.
 9. The method claimedin claim 6, further comprising sending a command to a snow meltingcomponent according to the reported at least one numerical value. 10.The method claimed in claim 9, further comprising operating the snowmelting component according to the command.